A sand core is used for forming internal cavities in a cast item, such as a die cast item. For example, a sand core is typically inserted between two halves of a casting die prior to introduction of a molten metal into the die. After solidification of the metal, the die halves are separated and the cast item is removed. Subsequently, the sand core is broken apart and removed from the cast item. By such a process, a cast item may be produced with internal cavities of desired size and shape.
Currently, many vehicle manufacturers use die casting and/or other casting processes to produce vehicle components—such as vehicle engine parts. In order to produce cast vehicle components, a sand core is frequently employed as described above. These sand cores are commonly molded from a mixture of silica sand grains and a resin binder for coating and binding the silica sand grains. Silica sand contains SiO2 as a main component thereof.
It has been determined that the type of sand used to make a sand core can affect the maximum density of the sand core. The type of sand may also affect the fluidity/flowability of the composition used to make the sand core. For example, the density of a sand core and fluidity/flowability of a sand core composition may be affected by the shape of the sand grains (e.g., spherical, mixed spherical and non-spherical, etc.) These factors, individually or collectively, may result in a weak sand core. A weak sand core may be broken during its removal from a sand core forming mold and/or during an associated metal casting process. If a core breaks during a metal casting process, problems such as, for example, veining in the cast product may occur.
Consequently, it can be understood that there is a need for a sand core composition having sufficient fluidity to permit the precise and repeatable molding of sand cores of desired size and shape, which sand core composition will also result in sand cores of sufficient strength to withstand the pressures of an associated casting process. Exemplary sand core compositions of the present invention satisfy these needs/preferences.